One common type of electromechanical switch used in a variety of different fields of technology includes the basic coil-armature device, such as, for example, a solenoid. The basic coil-armature device traditionally comprises a coil of wire, usually fashioned in cylindrical form, around some form of moveable core or armature. The introduction of an electric current through the coil of wire generates an electromagnetic field, which, in turn, attracts the moveable core, drawing it into the center of the coil. The movement of the armature is typically designed to interface a variety of different types of systems, such as, for example, an electrical contact or a valve.
Traditionally, a coil-armature device is activated by introducing a large initial current through the coil, thereby generating an electromagnetic field with sufficient strength to overcome system frictions and loads in order to rapidly attract the armature into the center of the coil. Once the armature is attracted to or retracted into the coil, the coil-generated electromagnetic field is maintained in order to hold the armature in place. However, the amount of power necessary to hold the armature in place after it has been retracted into the coil is but a fraction of the original amount of power necessary to draw the armature into the coil.
Typical coil-driving circuits apply a high level of current to the coil in order to initiate retraction of the armature. However, once the armature is retracted, these typical driving circuits continue to supply a high level of current to the coil to hold the armature in place. This use of excessive current to hold the armature in place not only results in a significant waste of energy, but also significant costs associated with the design and construction of a coil-armature device that is capable of handling high levels of current for an extended duration of time, as well as the buildup of heat associated with the high current levels.
The embodiments described hereinafter were developed in light of these and other problems identified by the inventors.